1. Field of the Invention
The invention relates to a process for the production of tetronic acid from 4-haloacetoacetic ester.
2. Prior Art
Tetronic acid, which is used among other things as an accelerator for photographic development, is known to be produced from 4-mono-haloacetoacetic ester or acid. According to the Swiss Pat. No. 503,722, 4-chloroacetoacetic ester is reacted with an aromatic amine to produce 3-arylaminocrotolactone, and the tetronic acid is liberated from such lactone by means of a mineral acid. The disadvantage of such method is that the isolation of the tetronic acid can only be realized by means of high vacuum sublimation. According to Swiss Pat. No. 529,128, 4-haloacetoacetic acid is reacted with alkali in aqueous solution. By treatment with a mineral acid the tetronic acid is liberated. Here too the isolation of the tetronic acid must be accomplished by means of high vacuum sublimation; moreover, the achieved yield is only 43 to 44 percent.